PubMed · 15035770
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Dana Braner, Barry Markovitz. Digital image compression: pixels n' bits.. https://doi.org/10.1177/0885066603254290
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Digital technology transforms analog signals into digital signals. Digitalization translates data into a numerical sequence of 0 seconds and 1 second or off and on (binary system). Thus encoded, differing signals (static or moving images, sounds, written texts) become homogeneous and can be handled simultaneously in a rapid and flexible manner while maintaining quality and stability. In digital format, data are easy to handle and can be compressed without undergoing any alteration of their contents, creating a vast wealth of information contained in little space, as in digital libraries.
An improved directly digital flow controller is evaluated for its ability to modulate gas flow rates. As in the older device, the "GasDAC" (named for its similarity to a weighted-resistor digital-to-analog converter) is capable of controlling gas flow in a linear and reproducible manner with the advantage of having an adjustable range of flow rates. The new design incorporates venting to prevent "puffing" when the individual flow channels are opened. The temporal characteristics of the GasDAC are also examined; modulation frequencies of 10 Hz with various types of waveforms are possible with the new device.
In this paper, two new analog CMOS comparators (Type-I and Type-II) with low-voltage and wide-input capabilities are proposed. The comparator receives two analog inputs and puts out one digital state to identify the larger (or the smaller) of the input variables, which represents an useful operation in data conversion and sensory signal processing. Without using special fabrication technologies, the supply voltage of the circuit is reduced to 1 V. Due to the utilization of CMOS back-gate technique, the input range of the comparators is greatly improved. The comparators are composed of bulk-driven stage and dynamic latch. By using a CMOS n-well technology, the results of HSPICE simulations indicate that the response time of Type-I circuit is 1 micros under 10 mV identified resolution. Type-II comparator achieves 5 mV identified resolution. The input dynamic ranges of the comparators are approximately rail-to-rail.